Increasing road traffic and corresponding congestion has various negative effects. Accordingly, efforts have been made to combat increasing traffic congestion in various ways, such as by making information about current traffic conditions available. Such current traffic information may be provided to interested parties in various ways (e.g., via radio broadcasts, an Internet Web site that displays a map of a geographical area with color-coded information about current traffic congestion on some major roads in the geographical area, information sent to cellular telephones and other portable consumer devices, etc.). One source for information about current traffic conditions includes observations manually supplied by humans (e.g., traffic helicopters that provide general information about traffic flow and accidents, reports called in by drivers via cell phones, etc.), while another source in some larger metropolitan areas is networks of traffic sensors capable of measuring traffic flow for various roads in the area (e.g., via sensors embedded in the road pavement). Unfortunately, various problems exist with respect to such information, such as related to the accuracy and coverage of the information, as well as to similar information provided by other sources.
One use of road traffic information is for commuters and other passengers in areas having multiple alternative types of transportation. However, various problems exist with attempting to plan and take trips that include transportation other than private vehicles on public roads.